WO2001043882A1

WO2001043882A1 - Centrifugal classifier

Info

Publication number: WO2001043882A1
Application number: PCT/JP1999/007047
Authority: WO
Inventors: Jun Ohashi
Original assignee: Tomoe Engineering Co., Ltd.
Priority date: 1999-12-15
Filing date: 1999-12-15
Publication date: 2001-06-21
Also published as: KR100494228B1; JP3775659B2; KR20020066326A

Abstract

A centrifugal classifier that is reduced in size and capable of reliably and efficiently separating sediment and suspended matter from a raw liquid and capable of sufficiently washing separated substances, the classifier being also superior in drainage efficiency. Installed on the shaft barrel (30a) of a screw conveyor (30) are a plurality of plate vanes (33) extending axially and radially on the inner diameter side of a spiral vane (31). The outer end edge of each plate vane is positioned between the liquid level in a bowl (20) and the inner peripheral surface of the bowl, and the spiral vane is rotated along the outer end edges of the plate vanes. And the space between adjoining plate vanes on the inner diameter side of the spiral vane is a suspended matter conveyance passage (R). Further, the position close to a dam (24) in the inner peripheral surface of the bowl is tapered such that the diameter is gradually reduced toward the front. Further, a suspended matter drainage region (25) is tapered such that the diameter is gradually increased toward the suspended matter outlet (26) at the front end.

Description

Description Centrifugal sorting equipment Technical field

According to the present invention, a screw conveyor is inserted in a cylindrical bowl, and these are rotatably supported relative to each other. A decanter-type separator separates sediment and suspended matter from a stock solution supplied into the bowl. Centrifugal sorting apparatus. Such a centrifugal separation device not only separates resins with various specific gravities, such as separation of PVC (PVC) and PE (polyethylene) in the recycling of crushed waste plastics, but also has specific gravities. Used to separate multiple types of solids. Background art

As a general deccan-type centrifuge, for example, the one shown in FIG. 8 is known. This is because the undiluted solution is separated into settled particles and medium liquid in the bowl 1 by centrifugal force, and the settled particles are conveyed by the screw conveyer 2 with a slight rotation difference from the bowl 1; The bowl 1 is configured to be discharged from the left end.

However, the centrifugal separator is designed for the purpose of separating a liquid and a sedimentable solid, and most of the suspended matter contained in a trace amount in the processing stock solution is discharged out of the machine together with the medium liquid. Basically, the floating material transport mechanism is not considered, and some of the floating material may be discharged to the left end of Fig. 8 together with the sediment by the spiral blade. Therefore, when a stock solution containing a large amount of suspended matter is treated, it is not only impossible to separate the suspended matter from the sediment, but also the suspended matter is not smoothly discharged out of the machine, and the inside of the machine is blocked. There is also a risk. Even if the suspended matter is discharged by devising such as increasing the ratio of the liquid in the undiluted solution, the suspended matter and the liquid are not separated in the machine.To separate them, for example, a basket type Separately, a process using a centrifuge or another solid-liquid separator was required.

In order to solve such inconveniences, for example, a wet separation apparatus and the like described in Japanese Patent Application Laid-Open No. 6-178948 have been proposed. This device has two screw conveyors wound in opposite directions on one shaft passing through the axis of the bowl, and one of the screw conveyors conveys the sediment to one end of the rotating container. Then, the floating material is conveyed to the other end of the rotating container by the other reverse-wound screw conveyor. In this wet-type separator, the outer diameter of the reverse-wound screw conveyor for transferring suspended matter at the other end of the bowl substantially at the center is set up to the middle between the liquid level and the inside diameter of the bowl. There is no means to transport the sediment to one end of the rotating container up to the inner diameter of the bowl. Therefore, during operation, the sediment that has accumulated between the outer diameter of the reverse-wound screw conveyor for floating material transfer and the inner diameter of the bowl due to the movement of the reverse-wound screw conveyor for floating material transfer is reduced. There is a problem that the equipment cannot be transported and discharged outside the equipment, and the equipment must be periodically stopped, disassembled, and removed.

In the wet separation apparatus, the screw conveyor on the sediment side conveys the sediment pressed against the inner diameter of the bowl by centrifugal force. However, the reversely wound screw conveyor for conveying the suspended matter uses the liquid near the liquid surface of the bowl. It is merely a circling of the suspended matter floating with the liquid along with the suspended matter, and the efficiency of transporting the suspended matter to the other end is poor. In addition, since the medium liquid outlet is located at one end from the processing solution input port, when the suspended matter is conveyed to the other end of the rotating container by a screw, the flow of the medium liquid is the conveyance of the suspended matter. The direction is opposite to the direction, and it is easily anticipated that the efficiency of transporting suspended matter will be further reduced. Conveyance of suspended matter If the rate decreases, the accuracy of sedimentation and specific gravity separation of suspended matter will naturally decrease.

The present invention has been made in view of the above-mentioned problems of the prior art, and it is possible to reliably and efficiently separate sediment and suspended matter from a stock solution without increasing the size of the entire apparatus. It is an object of the present invention to provide a centrifugal separation apparatus that can sufficiently wash the separated substances and can also excel in dewatering efficiency. Disclosure of the invention

The gist of the present invention to achieve the above-mentioned object lies in the following inventions.

[1] A centrifugal separation device that separates and collects sediment and suspended matter from a stock solution of a solid-liquid mixture, and has a cylindrical bowl 20 that rotates at a high speed, and is inserted into the bowl and has a different speed coaxially with the bowl. A screw conveyor 30 that can be rotated with a pump, a sediment outlet 23 that is provided at one end of the bowl, and a dam 2 that is provided at the other end of the bowl and regulates the liquid level in the bowl. A centrifugal separation apparatus comprising: a supply means for supplying a stock solution of the solid-liquid mixture; a driving means for the bowl; and a means for generating a differential speed between the bowl and the screw conveyor. A plurality of plate blades extending in the radial direction and extending in the radial direction at the inner diameter side of the spiral blade toward the dam portion on the shaft body are disposed on the shaft body portion. And the outside of each plate blade Around the other end of the spiral blade along the edge, the space between the respective plate blades on the inner diameter side of the spiral blade is set as a floating material transport path R, and a dam portion is formed from one end of the floating material transport path. A centrifugal separation device characterized by opening a stock solution supply port 34 on the shaft body of the screw conveyor on the side.

[2] The inner peripheral surface of the bowl 20 at a position close to the dam portion 24 is at one end side. [10] The centrifugal separator 10 according to [1], wherein the centrifugal separator has a tapered shape whose diameter gradually tapers toward the dam side.

[3] In the dam section 24, the overflow portion (dam top) where the medium liquid and the suspended matter separated from the undiluted solution passes over is inclined in such a direction that the liquid depth gradually decreases toward the overflow side. The centrifugal sorting device 10 according to [1] or [2], characterized in that:

[4] On the other end side of the dam portion 24 of the bowl 20, there is formed a floating material draining portion 25 through which the medium liquid and the suspended matter that has passed over the dam portion are guided, and the floating material draining portion is a dam. It has a filter medium 28 forming an inner layer and a filter medium supporting part 29 forming an outer layer in a tapered shape in which the diameter gradually widens from the section side to the other end side. Filter medium support section has a medium liquid discharge passage 27, and a floating substance outlet 26 is provided on the other end side of the floating substance draining section. The centrifugal separator 10 according to [1], [2] or [3], which is characterized in that: BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a longitudinal sectional view showing a centrifugal sorting device according to a first embodiment of the present invention.

FIG. 2 is an enlarged longitudinal sectional view showing a main part of the centrifugal sorting device according to the first embodiment of the present invention.

FIG. 3 is a cross-sectional view taken along the line III-III in FIG.

FIG. 4a is a sectional view showing the configuration of the first dam portion.

FIG. 4b is a sectional view showing the configuration of the second dam portion.

FIG. 4c is a sectional view showing the configuration of the third dam portion.

FIG. 5 is a longitudinal sectional view showing an example in which a part of a plate blade of the centrifugal sorting device according to the first embodiment of the present invention is bent. FIG. 6 is a longitudinal sectional view showing a centrifugal sorting device according to a second embodiment of the present invention.

FIG. 5 is a longitudinal sectional view showing a centrifugal sorting device according to a third embodiment of the present invention.

FIG. 8 is a longitudinal sectional view schematically showing a general decane-type centrifuge. BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, various embodiments representing the present invention will be described with reference to the drawings. 1 to 5 show a first embodiment of the present invention. As shown in FIG. 1, the centrifugal separation device 10 according to the present embodiment includes a bowl 20, a screw conveyer 30, a gear box 14, and a processing device, as shown in FIG. It has a feed tube 19 for stock solution, stock solution supply port 34, cone section 21 and sediment outlet 23, etc., and screw screwer 30 is inserted into cylindrical bowl 20 and relatively rotated. The bowl is supported as possible, and is configured to separate the stock solution supplied into the bowl by centrifugal force. The basic structure and functions of these are basically the same as those of the conventional deccan-type centrifuge, and detailed description is omitted.

However, the present embodiment differs from the conventional decanter centrifuge in several points. First, the shaft body 3 of the screw conveyor 30

At 0 a, a plurality of plate blades 3 3, 3 3 are provided which extend in the axial direction toward a dam portion 24 described later on the inner diameter side of the spiral blade 31 and also spread in the radial direction. . As shown in FIG. 3, in the present embodiment, a total of four plate blades are arranged so as to spread in the radial direction at an equal angle. The outer edge 3 3a of each plate blade 33 is set to be located between the liquid level in the bowl 20 and the inner peripheral surface of the bowl, and extends along the outer edge of each plate blade. The other end of the spiral blade 3 1 A part of the spiral blade is supported so as to go around, and a space between the plate blades located on the inner diameter side near the other end of the spiral blade is set in the floating material transport path R. As described above, the suspended matter transport path is formed only in a part near the other end of the bowl in the axial direction of the spiral blade. The undiluted solution supply port 34 for supplying the undiluted solution into the bowl is opened at a predetermined position in the area of the suspended matter transport path, and the dam part in the bowl is located at a position close to the other end of the suspended matter transport path. It is arranged in.

The inner peripheral surface of the bowl 20 at a position close to the dam portion 24 is provided with a tapered portion 40 whose gradual diameter tapers toward the dam portion. In addition, a dam portion 24 with a slope at the top of the dam shown in Fig. 4a and a floating material draining portion 25 are provided at the other end (left side) of the dam, respectively. At the other end of the, there are several suspended matter outlets 26 in the circumferential direction.

According to the centrifugal separation device 10 of the present embodiment, the undiluted solution supplied into the bowl 20 floats in the bowl under the action of centrifugal force (usually about 300 G to 1500 G). The sediment and sediment are separated in the medium liquid. For example, when two kinds of plastics are separated from waste plastic, a medium liquid having an intermediate specific gravity of these specific gravity is mixed with waste plastic to obtain a stock solution, and a predetermined depth set in advance in a dam portion 24 in a bowl. I'm stuck. Among the solids separated by the action of centrifugal force, sediment with a specific gravity higher than that of the medium liquid settles toward the inner peripheral surface of the bowl, and suspended substances with a specific gravity smaller than that of the medium liquid are leveled in the bowl. Surface. The sediment is conveyed by the spiral blade 31 of the screw conveyor 30 to the cone 21 where the gradual shape at one end of the bowl tapers, and is subjected to the liquid removal action by centrifugal force. Is discharged from the sediment exit 23 at the end of the

On the other hand, the suspended matter is carried to the dam portion 24 side along the flow of the medium liquid in the suspended matter transport path R. Decane evening centrifugation without intentional separation of suspended matter In the case of a take-off machine, the spiral blades of the screw con- veyor are installed from the shaft body to almost the entire inner surface of the bowl. Therefore, the medium liquid flowing over the dam in the stock solution charged into the machine needs to travel a long distance along the spiral blade, whereas according to the suspended matter transport path according to the present invention, the medium liquid is Since the suspended matter transport path can be easily moved in the axial direction, the suspended matter existing near the liquid surface is also efficiently transported in the direction of the dam portion along with the flow of the medium liquid. Further

Since the tapered portion 40 is provided at a position close to the dam portion 24, the flow velocity of the medium liquid and suspended matter in the stock solution increases as approaching the dam portion, so that the suspended matter is more easily discharged. Become.

Here, the spiral blade 31 facing the floating material transport path R is provided on the inner peripheral surface side of the bowl 20 while keeping a sufficient distance from the liquid surface. It does not affect the transport of suspended matter in the axial direction. That is, in the present invention, the transport areas of the sediment and the suspended matter overlap inward and outward in the radial direction, and overlap each other in the axial direction. As a result, it is possible to secure a sufficient separation area between suspended matter and sediment within a limited length of the apparatus without incurring an increase in the size of the entire apparatus, and to achieve sediment and suspended matter from the undiluted solution. Can be reliably separated, and can be transported efficiently.

Most of the suspended solids and sediment contained in the undiluted solution are separated in the medium liquid immediately after being introduced into the machine. However, if particles of suspended matter and sediment adhere to each other, the average specific gravity may be close to the specific gravity of the medium liquid.In this case, the adhered particles are transported in the direction of the dam part 24 along with the flow of the liquid. Are separated by the shearing action due to the movement of the liquid during transportation. Also, the adhered particles settle, and the bowl 2

Even when the particles are conveyed to the inner peripheral surface, they are separated by the stirring action with other particles in the process of being conveyed by the spiral blade. Once the adhered particles separate

Due to the effect of centrifugal force, suspended matter is directed toward the liquid surface, and sediment is directed toward the inner surface of the bowl. Move quickly to. The sediment that has reached the inner peripheral surface of the bowl is moved in the direction of the sediment outlet 23 by the spiral blade, and the suspended material that has reached the vicinity of the liquid surface reaches the dam part 24 by riding the flow of the medium liquid.

A conventional dam is formed by appropriately providing an opening in a plate-like member perpendicular to the rotation axis of the bowl, and the dam top is parallel to the liquid level. Therefore, the liquid inflow side at the top of the dam is composed of a substantially right-angled ridgeline.When suspended matter larger than the liquid depth reaches the dam, it is caught at the ridgeline at the top of the dam and the gap between the suspended matter It is possible that only liquid will escape from the system.

On the other hand, the dam portion 24 of the present invention is provided with a slope at the top of the dam, and by setting the distance between one end of the top of the dam and the liquid surface sufficiently larger than the size of the suspended matter, The trapping described above does not occur, and even if the suspended matter is larger than the liquid depth at the other end of the dam, the flow of the medium liquid pushes up the suspended matter along the slope and can easily overflow the dam.

FIG. 4 shows the shape of the dam portion 24 described above in more detail. Figures 4a, 4b, and 4c each consist of a cross-sectional view taken along a plane perpendicular to the rotation axis (left figure) and a cross-sectional view taken along a plane containing the rotation axis (right figure). .

First, a comparison with a cross-sectional view (left figure) cut along a plane perpendicular to the rotation axis shows that

Fig. 4a shows a case where the entire inner surface of the annular member 24a is used as a dam.

This is effective when the suspended particles are relatively small or when the liquid volume is relatively large compared to the suspended mass. On the other hand, FIG. 4b shows a cutout 24b provided in a part of the annular member of FIG. 4a, and as shown in the drawing, the height of the liquid can be increased. Even if the particles of the suspended matter are relatively large, they can smoothly overflow. FIG. 4c shows an example in which an opening is provided in a portion including the liquid surface of the ring-shaped member. In this case, by placing the dam top concentrically with the liquid surface, a large liquid height and maximum outflow width can be obtained. be able to.

Next, comparing the sectional views (right figure) cut along the plane including the rotation axis, Fig. 4a and Fig. 4c show that the entire area of the dam top is inclined, In this case, only the right side of the top of the dam is sloped, but in either case, it is effective for the smooth discharge of suspended matter. The entire area of the dam top does not need to have a slope, and if the distance between one end of the dam top and the liquid surface is larger than the maximum size of the suspended matter, the other end of the dam top will be parallel to the liquid level. No problem. The suspended matter draining section 25 has a tapered shape gradually increasing in diameter from the dam side toward the other end, and has a filter medium 28 forming an inner layer and a filter medium supporting section 29 forming an outer layer. Has a large number of micropores or slits through which the medium liquid passes, the filter medium support section has a medium liquid discharge passage 27, and a floating substance outlet 2 is provided at the other end of the floating substance draining section. 6 are provided.

The mixture of the medium liquid and the suspended matter that has reached the suspended matter draining section 25 after flowing over the dam section 24 temporarily stays on the surface of the filter medium 28, and the medium liquid contains a large number of small liquids provided in the filter medium. After passing through the hole or the slit, it passes through the medium liquid discharge passage 27 provided in the filter medium support portion 29 and is discharged outside the machine. On the other hand, the suspended matter temporarily staying on the surface of the filter medium forms a layer of a certain thickness, but the component of the pressure and centrifugal force of the suspended matter continuously supplied from the dam part in the direction of the filter medium surface By the action of, it is gradually conveyed to the other end and discharged out of the machine from the suspended matter outlet. Therefore, continuous and stable discharge of suspended matter can be achieved while ensuring sufficient liquid removal, without special provision of a discharge means such as a compa paddle in the suspended matter dewatering section 25.

The filter medium 28 is made of a material having a large number of micropores or slits sized according to the particle size of the suspended matter. Specifically, in addition to punch hole screens and edge wire screens that have been used in the past, porous ceramic moldings and segment-type screens (divided block screens) have been used. ) Or the like.

As described above, in the centrifugal separation apparatus 10 according to the present embodiment, the processing stock solution introduced into the machine by the feed tube 19 is efficiently separated into three components: sediment, suspended matter, and medium liquid. And is continuously discharged outside the machine. The interior of the casing 11 shown in FIG. 1 is divided into a sediment outlet 23, a medium liquid discharge passage 27, and a suspended matter outlet 26 in the bowl 20, respectively. And sediment, media and suspension can be collected separately.

FIG. 6 shows a second embodiment of the present invention.

In the present embodiment, in the suspended matter draining section 25, the portion close to the dam section 24 has a tapered shape (steeply inclined portion) that widens at a steep angle (predetermined angle) toward the other end. The other portion has a tapered shape (slowly inclined portion) which is directed toward the other end side and diverges at a gentler angle to the rotation axis of the bowl 20 than the predetermined angle.

In other words, the suspended matter that stays in the gentle slope for a certain period of time and is sufficiently drained is pushed out by the suspended matter that is sent sequentially from the sharp gentle slope, and while maintaining good liquid removal property in the gentle slope, Stable discharge of suspended matter can be realized. With this mechanism, even if the shape and size of suspended particles fluctuate, they can be constantly discharged. In FIG. 6, the cross section of the filter medium is composed of two straight lines, but the line segment that constitutes the cross section of the filter medium may be composed of three or more straight lines, and a part thereof is formed by using a curve. Is also good.

In the third embodiment of the present invention shown in FIG. 7, not only separation of suspended matter and sediment but also a function of washing them inside the machine is added. In the present embodiment, a straight portion for draining the sediment, which has a diameter substantially the same as that of the tip end of the cone portion, is further provided on one end side of the cone portion 21 on one end side of the bowl 20. Is formed, and a sediment outlet 23 is provided at the tip side of the storage portion. The slate portion is provided with a filter medium 28 a and a medium liquid discharge passage 27 a, similarly to the suspended matter draining portion 25.

In the present embodiment, the fixed feed tube 19 is a double tube, which is divided into a stock solution supply inner tube 19a and a rinse solution outer tube, and furthermore, a rinse solution outer tube. Is internally divided into two parts corresponding to the rinse pipe 19b and the rinse pipe 19c. The rinse pipe 19b and the rinse pipe 19c have openings at different positions in the direction of the rotation axis, and the respective liquid reservoirs provided on the inner peripheral surface of the shaft body (not shown) Supply the cleaning liquid to. The sediment washing liquid is ejected from the sediment washing means 35a projecting from the liquid reservoir. The washing liquid for suspended matter is sent from the liquid reservoir to the suspended matter draining section via the suspended matter rinse pipe 35c, and is ejected from the suspended matter washing means 35b provided there. .

Further, in the present embodiment, a partition plate 41 is provided in the middle of the shaft body 30a of the screw conveyer 30 passing through the suspended matter draining section 25. Sufficient clearance is provided between the outer peripheral edge of the partition plate and the inner peripheral surface of the suspended solids drainage section so that suspended solids do not clog. This partition plate has the effect of preventing the medium liquid from scattering to the discharge side and also preventing the cleaning liquid from flowing to the dam portion 24 side, so that higher cleaning efficiency can be obtained.

According to the present embodiment as described above, the sediment is in the slate part 22 and the suspended matter is in the suspended matter draining part 25 by the cleaning liquid 35 a and the cleaning liquid ejected from the cleaning means 35 b. It is thoroughly washed. The in-machine cleaning mechanism according to the present embodiment is particularly effective when the stock solution contains components that hinder the use of suspended matter and sediment in the post-process, because the post-process cleaning can be omitted. It is.

In the present invention, the number of plate blades is not limited at all.

Two or another number may be used. Also, the shape of each plate blade 3 3 is not necessarily It does not need to be flat, and for example, the range in which a part of the suspended matter comes into contact with the inner surface of the dam part 24 and the part of the inner peripheral surface close to the dam part of the taper part 40 of the bowl 20 will be described. If a part of the other end of the plate blade is bent or curved as shown in FIG. 5, a force toward the dam portion can be applied to the floating material near the dam portion to improve the efficiency of discharging the floating material.

In addition, the suspended matter transport path R according to the present invention can be obtained by removing most of the spiral blades located near the liquid surface of the processed material, in addition to the method using the plate blade as described above. For example, a method in which a number of openings are provided in the spiral blade 31 or a method in which the spiral blade in the floating material transport path region is connected to the shaft body 30a of the screw conveyer 30 by a spoke-shaped member may be used. Industrial applicability

As described above, the centrifugal separation device according to the present invention can efficiently separate two or more types of solids having different specific gravities while reducing the size of the entire device. Whereas conventional centrifuges have many advantages with respect to separation of medium liquid and sediment, the centrifugal separator according to the present invention has many structural characteristics, and those characteristics are mainly It has already been explained that it exerts its effect on the separation and washing of suspended matter.

When an in-machine washing function is added to the centrifugal sorting device according to the present invention, it can be effectively used particularly for recycling waste plastic. For example, resins having a specific gravity of 1 or more, such as polystyrene, ABS, polycarbonate, PET,

When separating two types such as PBT and polyamide, salt and sodium hydroxide may be dissolved in water in order to make the specific gravity of the medium liquid between two types of resins. In such a case, it is preferable that the separated suspended matter and sediment do not contain these medium liquid additives, and the in-machine washing function of the centrifugal sorting apparatus according to the present invention becomes extremely effective. In order to separate the polyolefin resin from other resins, if water is used as a medium liquid, the separation itself is easy.However, for the purpose of washing, a surfactant, acid or alcohol is added to the water. In this case, removing these additives by washing inside the machine contributes to shortening the process.

Furthermore, in the case of the PET bottle recycling process, it may be exposed to soil and dust during the recovery process, and it is unavoidable that the PET bottle is mixed into the processed material. These sedimentable fine particles are removed to some extent in the process of adjusting the stock solution to be treated. When supplied to the centrifugal separation device according to the present invention, they are conveyed together with the sediment to the sediment exit side. Therefore, according to the device of the third embodiment of the present invention shown in FIG. 7, the openings of the small holes or slits of the filter medium 29a of the straight portion 22 are set appropriately. As a result, these fine particles can be discharged out of the machine together with the washing liquid, and a higher-purity sediment can be recovered.

Claims

The scope of the claims

1. A centrifugal separation device that separates and collects sediment and suspended matter from a stock solution of a solid-liquid mixture, and has a cylindrical bowl (20) that rotates at high speed, and is inserted into the bowl at a different speed coaxially with the bowl. A rotatable screw conveyor (30), a sediment exit (23) provided at one end of the bowl, and a dam (24) provided at the other end of the bowl to regulate the liquid level in the bowl. ), Means for supplying a stock solution of the solid-liquid mixture (19), means for driving the bowl, and means (14) for generating a differential speed between the bowl and the screw conveyor.

On the shaft body of the screw conveyor, a plurality of plate blades extending in the axial direction toward the dam portion on the inner diameter side of the spiral blade and extending in the radial direction are disposed, and the outer edge of each plate blade is Between the liquid surface in the bowl and the inner peripheral surface of the bowl, and along the outer edge of each plate blade around the other end of the spiral blade, between each plate blade on the inner diameter side of the spiral blade. This space is set as a suspended matter transport route (R), and an undiluted solution supply port (34) is opened in the shaft body of the screw conveyor on the dam side from one end of the suspended matter transport route. Centrifugal separator.

2. The inner peripheral surface of the bowl (20) at a position close to the dam portion (24) is tapered so that the diameter gradually decreases from one end toward the dam. The centrifugal separation device (10) according to item 1.

3. The dam section (24) is characterized in that the overflow portion where the medium liquid and suspended matter separated from the undiluted solution gets over is provided with an inclination in a direction in which the liquid depth gradually decreases toward the overflow side. The centrifugal separation device (10) according to claim 1 or 2.

4. At the other end of the bowl (20) from the dam portion (24), there is formed a floating material draining portion (25) through which the medium liquid and the floating material having passed over the dam portion are guided. The suspended matter draining section has a tapered shape in which the diameter gradually widens from the dam side toward the other end, and a filter medium (28) forming an inner layer and a filter medium supporting section (29) forming an outer layer. The filter medium has a number of micropores or slits through which the medium liquid passes, the filter medium support has a medium liquid discharge passage (27), and 4. The centrifugal separation device (10) according to claim 1, wherein a suspended matter outlet (26) is provided at the other end of the liquid part.